ABSTRACT: This proposal is submitted to request a continuation of the research conducted during the K18 Career Enhancement Award in Stem Cell Research (02/01/07-01/31/09). In this proposed research, further investigation to enhance in vivo cellular and molecular MRI of mESC survival and proliferation (teratoma formation) following transplantation into the myocardium is described. The rationale of this research comes from a fundamental notion underlying regenerative medicine: the transplanted cells must survive to trigger a complex cascade of biological processes to regenerate and restore the injured myocardium permanently. Although MRI has become one of the predominant modalities to track ex vivo labeled cells and to evaluate functional restoration of the recipient myocardium, definitive information on cellular viability and proliferation can not be assessed in vivo. This research study proposes to develop robust in vivo MRI methods to detect and quantitate viable cells following delivery into the injured myocardium, which will enable accurate assessment of therapeutic efficacy of regenerative medicine while also monitor for potential teratoma formation. Novel MRI methods, innovative cellular and molecular techniques, and an array of established methodologies have been integrated to study 3 hypothesis driven Specific Aims: Specific Aim 1 Manganese (Mn2+)-guided in vivo cellular MRI will enable longitudinal evaluation of mESC survival following transplantation into the injured murine myocardium. Specific Aim 2 Reporter gene (RG)-guided in vivo molecular MRI of genetically engineered cells will enable longitudinal evaluation of mESC survival following transplantation into the injured murine myocardium. Specific Aim 3 Optimal quantity of viable mESC will restore the injured myocardium and minimize teratoma formation. This research proposal outlines a rigorous study of in vivo cellular and molecular MRI to address a fundamental challenge in regenerative medicine: mESC survival and abnormal proliferation following delivery into the injured myocardium. This proposal has been designed to advance in vivo cellular and molecular MRI methods with demonstrated proof-of-concept. High spatial and temporal resolution of MRI will be optimized with viability-specific cellular and molecular signal amplification techniques to generate quantitative data on cell survival and teratoma formation following transplantation into target organ. Upon successful conclusion of this research, a comprehensive MRI platform will be developed to quantitate cellular viability, proliferation, and myocardial restoration. Cross-disciplinary application of this nascent technology will provide enabling technology to assess fundamental stem cell biology of any transplanted cell and evaluate recipient tissue function of any human organ. Public Health Relevance Statement (provided by applicant): Stem cell research stands at a critical juncture. Recent development in nuclear reprogramming of human skin cells to generate pluripotent stem cells and directed differentiation of human embryonic stem cells into cardiomyocyte may lead to significant clinical breakthrough in the treatment of congestive heart failure, a public health epidemic. The proposed in vivo MRI system represents a dedicated platform to enable systematic translation of basic stem cell science to clinical application.